Optical brightening agent

ABSTRACT

An optical brightener comprising one or more spiro compounds of the formula (I),                    
     where 
     K 1  and K 2 , which are identical or different, are conjugated systems, and ψ is C, Si, Ge, Sn or Pb, is notable for high fluorescence quantum yields and a high temperature stability.

DESCRIPTION

According to Römpps Chemie Lexikon (Römpp Hermann [original author];Falbe, Jürgen [editor]; Chemie Lexikon, Georg Thieme Verlag, Stuttgart1991) optical brighteners are chemical compounds which remove grayingand yellowing from textiles, paper, plastics etc.; like dyes, they aredrawn out of the liquor onto the fiber or are incorporated into thematerial in question, and bring about brightening and at the same timesimulate a bleaching action by converting (invisible) ultravioletradiation into (visible) light of longer wavelength. The ultravioletlight absorbed from the sunlight is reradiated as weak bluishfluorescence, i.e. in the complementary color of yellowing. Theseorganic luminescent pigments (fluorescent dyes) thus act like opticaltransformers.

Optical brighteners known from the prior art comprise, for example,derivatives of 4,4′-diamino-2,2′-stilbenedisulfonic acid (flavonicacid), 4,4′-distyrylbiphenylene, methylumbelliferone, coumarin,dihydroquinolinone, 1,3-diarylpyrazoline, naphthalimide, benzoxazole,benzisoxazole and benzimidazole systems linked via CH═CH bonds, orpyrene derivatives substituted by heterocycles.

Although the known optical brighteners achieve very good results, thereis a continuing need for novel improved systems since the requirements,for example as regards brightness, fastness toward sunlight, washing,ironing, additives simultaneously used, environmental compatibility andcost efficiency, are also continually increasing.

Surprisingly, it has now been found that organic spiro compounds whichcomprise a conjugated system are particularly suitable for use asoptical brighteners.

Spiro compounds have at least one tetravalent spiro atom which links tworing systems together. This is explained in the Handbook of Chemistryand Physics, 62nd ed. (1981-2), p. C-23 to 25.

The invention thus provides an optical brightener comprising one or morespiro compounds of the formula (I),

where K¹ and K², independently of one another, are conjugated systems,and ψ is C, Si, Ge, Sn, Pb, preferably C or Si, particularly preferablyC.

Compared with conventional optical brighteners, the compounds usedaccording to the invention have exceptional temperature stability. Thisis evident, for example, from the fact that the emission maximum of thecompounds after heating decreases only slightly, and in some cases notat all, and that in the case of many of these compounds, even anincrease in the emission maximum after heating is observed. This makesit possible to brighten those polymeric materials in which thebrightener can only be incorporated into the polymeric material in themelt process (in particular industrial polymeric materials, e.g. aramidfibers). The high temperatures required for this purpose lead, in thecase of the brighteners customary hitherto, to their thermaldecomposition. In the production of conventional fibers, the wetspinning process can here be replaced by the melt process, which issolvent-free and therefore to be preferred for ecological reasons.

Compared with brighteners known hitherto, as well as thermal stability,improved photostability, preferably in the case of carbocyclic aromaticsystems, is also achieved.

Because of the relatively high thermal and photochemical stabilitycompared with prior art brighteners, brightening is also possible infields of application which have hitherto been excluded. For example,these compounds can, in principle, also be used for brighteninggeotextiles and, because the brightener molecules have a low tendency tomigrate, packaging materials.

The fluorescence quantum yield of the spiro compounds in solution and inthe solid matrix can be greater than 95%. As a result, lower brightenerconcentrations are required for the same or, in most cases, improvedbrightening effect, which is advantageous both for cost reasons and forecological reasons. Aggregation phenomena, often a problem withconventional brighteners, do not arise in the case of spiro compoundsbecause of their structure. As a result, a favorable and, for some areasof application, necessary molecularly disperse distribution is achieved.The low tendency toward aggregation can be further utilized to achievevery high brightener concentrations, up to the pure, preferablyamorphous, compound, for example in the form of a film, but neverthelessto obtain a high fluorescence quantum yield, i.e. concentrationquenching does not take place.

Furthermore, these compounds are notable for high temperature stabilitywith regard to color stability and fluorescence quantum yield. Thismeans that the emission maximum in the range from 380 to 750 nm,measured at room temperature, decreases by no greater than 25%, relativeto the initial state, after the material, applied in a thickness of nogreater than 1 μm to a quartz substrate, has been heated to 250° C. inan inert atmosphere at a pressure no greater than 1 mbar for 30 min.

The reduction in the emission maximum is preferably no greater than 20%,particularly preferably 15%, relative to the initial state beforethermal treatment.

The invention thus further provides an optical brightener

a) which has a fluorescence quantum yield of ≧40%, preferably ≧50%,particularly preferably ≧60% in the, preferably amorphous, solid, and

b) the emission maximum in the range from 380 to 750 nm, measured atroom temperature, decreases by no greater than 25%, relative to theinitial state, after the material, applied in a thickness of no greaterthan 1 μm to a quartz substrate, has been heated to 250° C. in an inertatmosphere at a pressure no greater than 1 mbar for 30 min.

Using the Spiro compounds, it is also possible to adjust the color shadeby varying the substituents on the spirobifluorene parent substance.

For some applications, for example as effective, thin UV filters, it isalso advantageous if the spiro compounds used according to the inventioncan be prepared amorphously. For filter applications it is advantageousif the compounds have very high extinction coefficients in the UVregion, preferably between 250 and 380 nm, and can be prepared in veryhigh brightener concentrations, up to the pure film (100%), asamorphous, thin films (for example by spin coating or sublimation).

The term amorphous is used to describe the state of solids whosemolecular building blocks are arranged not in crystal lattices, butirregularly. Unlike a crystal where there is short-range order (i.e.constant distances to the nearest neighboring atoms) and long-rangeorder (regular repetition of a base lattice) between the atoms, theamorphous state has only short-range order. The amorphous material hasno physically distinguishable direction; it is isotropic. All amorphoussubstances strive, to varying degrees, to achieve the more energeticallyfavorable crystalline state. In the diffraction of X-rays, electron raysand neutron rays, amorphous solids do not give sharp interference rings,as in a crystal, but only diffuse interference rings at low diffractionangles (halos).

The amorphous state is thus clearly distinguishable from thecrystalline, liquid or liquid-crystalline state.

Compared with many known systems, the spiro compounds according to theinvention are also readily soluble, particularly in polar solvents, inparticular dichloromethane and chloroform (>30 g/l), meaning that spincoating and film formation inter alia are possible.

Processability from aqueous systems is achieved by substitution of thespiro compounds for strongly polar groups, such as carboxylic acid,carboxylate, sulfonic acid, sulfonate and quatemary ammonium groups.

The emission properties of the compounds used according to the inventioncan be adjusted over the entire region of the visible spectrum throughthe choice of suitable substituents. Furthermore, the covalently bondedarrangement of the two parts of the spiro compound permits a molecularstructure such that in both halves of the molecule certain propertiescan be established independently of one another, e.g. an extension ofthe absorption region into the longwave UV.

Preferred compounds of the formula (I) are the 9,9′-spiro compounds ofthe formula (II).

where ψ is as defined above and the benzo groups can, independently ofone another, be substituted and/or fused.

Particular preference is given to spirobifluorenes of the formula (III),

where ψ is as defined above and the other symbols and indices are asdefined below:

K, L, M, N are identical or different and are a group of the formulae

R is identical or different and is as defined for K, L, M, N or is —H, alinear or branched alkyl, alkoxy or carboalkoxy group having from 1 to22, preferably from 1 to 15, particularly preferably from 1 to 12,carbon atoms, —CN, —NO₂, —NR²R³, —⁺NR²R³R⁴, NOR²R³, —Ar or —O—Ar,preferably —SO₂CH₃, —CF₃, halogen, —SO₃H, —SO₃Na(K), —PO(OC₂H₅)₂,—CH₃OSO₃—, —N(CH₃)₃ ⁺, —O—(CH₂)₂)—N⁺(CH₃)(C₂H₅)₂;

Ar is phenyl, biphenyl, 1-naphthyl, 2-naphthyl, 2-thienyl, 2-furanyl,where each of these groups can carry one or two radicals R,

m, n, p are 0, 1, 2, 3, 4, 5, where n is preferably 0;

X, Y are identical or different and are CR or nitrogen;

Z is —O—, —S—, —NR—, —CRR¹—, —CH═CH—, —CH═N—;

R¹ is as defined for R;

R², R³, R⁴ are identical or different and are H, a linear or branchedalkyl group having from 1 to 22 carbon atoms, —Ar, 3-methylphenyl.

Preferred compounds of the formula (III) are those of the formula(IIIa)-(IIIg):

IIIa) K═L═M═N and is a group of the formula:

R′═C₁-C₂₂-alkyl, C₂H₄SO₃ ⁻

IIIb) K═M═H and N═L and is a group of the formula:

IIIc) K═M and is a group of the formula:

R′═C₁-C₂₂-alkyl, C₂H₄SO₃ ⁻and N═L and is a group of the formula:

IIId) K═M and is a group of the formula:

and N═L and is a group of the formula:

R′═C₁-C₂₂-alkyl, C₂H₄SO₃ ⁻

IIIe) K═L═H and M═N and is a group of the formula:

IIIf) K═M and is a group of the formula:

R′═C₁-C₂₂-alkyl, C₂H₄SO₃ ⁻

and M═N and is a group of the formula:

IIIg) K═L and is a group of the formula:

and M═N and is a group of the formula:

R′═C₁-C₂₂-alkyl, C₂H₄SO₃ ⁻

Particularly preferred compounds of the formula (III) are those of theformulae (Illaa) to (IIIdb):

(Illaa) K═L═M═N and is a group of the formula:

(Illba) K═M═H and N═L and is a group of the formula:

(IlIca) K═M and is a group of the formula:

and N═L and is:

(IIIda) K═M and is a group of the formula:

(IIIab) K═L═M═N and is a group of the formula:

(IIIbb) K═L═H and M═N and is a group of the formula:

(IIIcb) K═L and is a group of the formula:

and M═N and is:

(IIIdb) K═L and is a group of the formula:

and M═N and is a group of the formula:

Very particularly preferred Spiro compounds are those of the formula(IV),

where the symbols are defined as follows:

K, L, M, N, R⁵, R⁶ are identical or different and are one of the groupsG1 to G11;

and R⁵, R⁶ can also be identical or different and can be hydrogen or alinear or branched alkyl, alkyloxy or ester group having from 1 to 22carbon atoms, —CN or —NO₂.

Particularly preferred spiro compounds of the formula (IV) are thecompounds listed in Table 1, in which the abbreviations G1 to G11 are asdefined in formula (IV).

TABLE 1 Spiro compounds of the formula (IV) R⁵ = R⁶ = hydrogen CompoundK L M N Spiro-1 G1 G1 G3 G3 Spiro-2 G1 G1 G4 G4 Spiro-3 G1 G1 G5 G5Spiro-4 G1 G1 G6 G6 Spiro-5 G1 G1 G7 G7 Spiro-6 G1 G1 G8 G8 Spiro-7 G1G1 G9 G9 Spiro-8 G1 G1 G10 G10 Spiro-9 G1 G1 G11 G11 Spiro-10 G2 G2 G2G2 Spiro-11 G2 G2 G3 G3 Spiro-12 G12 G12 G12 G12 Spiro-13 G13 G13 G13G13

Preference is also given to spiro compounds of the formula (V),

where A, B, K, L, M, N are identical or different and are as defined forK, L, M and N for the formula (III).

Preference is given to compounds of the formula (V) in which K, L, M, N,A and B are the groups G1 to G13 already listed above.

Especially preferred spiro compounds of the formula (V) are

2,2′,4,4′,7,7′-hexakis(biphenylyl)-9,9′-spirobifluorene,

2,2′,4,4′,7,7′-hexakis(terphenylyl)-9,9′-spirobifluorene

2,2′,4,4′,7,7′-hexakis(quaterphenylyl)-9,9′-spirobifluorene

2,2′,4,4′,7,7′-hexakis(pentaphenylyl)-9,9′-spirobifluorene

The spiro compounds used according to the invention are prepared bymethods known per se from the literature, as are described in standardworks on organic synthesis, e.g. Houben-Weyl, Methoden der OrganischenChemie, Georg-Thieme-Verlag, Stuttgart and in the appropriate volumes ofthe series “The Chemistry of Heterocyclic Compounds” by A. Weissbergerand E. C. Taylor (editors).

The preparation is carried out under reaction conditions which are knownand suitable for said reactions. Use can also be made here of variantswhich are known per se and are not mentioned in more detail here.

Carbospiro compounds (ψ=C)

Compounds of the formula (IIIa) are obtained, for example, starting from9,9′-spirobifluorene, the synthesis for which is described, for example,by R. G. Clarkson, M. Gomberg, J.Am.Chem.Soc. 52 (1930) 2881.

Compounds of the formula (IIIa) can be prepared, for example, startingfrom a tetrahalogenation in the 2,2′,7,7′ positions of9,9′-spirobifluorene and a subsequent substitution reaction (see, forexample, U.S. Pat. No. 5,026,894) or via a tetraacetylation of the2,2′,7,7′ positions of 9,9′-spirobifluorene with subsequent C—C linkageafter converting the acetyl groups into aldehyde groups, or constructinga heterocycle after converting the acetyl groups into carboxylic acidgroups.

Compounds of the formula (IIIb) can be prepared, for example, by amethod similar to those of the formula IIIa, the stoichiometric ratiosin the reaction being chosen such that the 2,2′ or 7,7′ positions arefunctionalized (see, for example, J. H. Weisburger, E. K. Weisburger, F.E. Ray, J. Am. Chem. Soc. 72 (1959) 4253; F. K. Sutcliffe, H. M.Shahidi, D. Paterson, J. Soc. Dyers Colour 94 (1978) 306 and G. Haas, V.Prelog, Helv. Chim. Acta 52 (1969) 1202).

Compounds of the formula (IIIc) can be prepared, for example, via adibromination in the 2,2′ position and subsequent diacetylation in the7,7′ position of 9,9′-spirobifluorene and subsequent reaction by asimilar method to that for the compounds IIIa.

Compounds of the formulae (IIIe)-(IIIg) can be prepared, for example, bychoosing suitably substituted starting compounds for the construction ofthe spirobifluorene, e.g. 2,7-dibromospirobifluorene can be obtainedfrom 2,7-dibromofluorenone and 2,7-dicarbethoxy-9,9-spirobifluoreneusing 2,7-dicarbethoxyfluorenone. The free 2′,7′ positions on thespirobifluorene can then be further substituted independently.

For the synthesis of the K, L, M, N groups, reference may be made, forexample, to

DE-A 23 44 732, 24 50 088, 24 29 093, 25 02 904, 26 36 684, 27 01 591and 27 52 975 for compounds containing 1,4-phenylene groups; DE-A 26 41724 for compounds containing pyrimidin-2,5-diyl groups; DE-A 40 26 223and EP-A 03 91 203 for compounds containing pyridin-2,5-diyl groups;

DE-A 32 31 462 for compounds containing pyridazin-3,6-diyl groups; N.Miyaura, T. Yanagi and A. Suzuki in Synthetic Communications 11 (1981)513 to 519, DE-A-3 930 663, M. J. Sharp, W. Cheng, V. Snieckus inTetrahedron Letters 28 (1987), 5093; G. W. Gray in J. Chem. Soc. PerkinTrans 11 (1989) 2041 and Mol. Cryst. Liq. Cryst. 172 (1989) 165, Mol.Cryst. Liq. Cryst. 204 (1991) 43 and 91; EP-A 0 449 015; WO 89/12039; WO89/03821; EP-A 0 354 434 for the direct linking of aromatics andheteroaromatics.

The preparation of disubstituted pyridines, disubstituted pyrazines,disubstituted pyrimidines and disubstituted pyridazines is given, forexample, in the appropriate volumes of the series “The Chemistry ofHeterocyclic Compounds” by A. Weissberger and E. C. Taylor (editors).

Heterospiro compounds(ψ═C)

The preparation is carried out under reaction conditions which are knownand suitable for said reactions. Use can here also be made of variantswhich are known per se and are not mentioned in more detail here.

Compounds of the formula (III) are obtained, for example, starting frombis[biphenyl-2,2′-diyl]silane (=9,9′-spirobi(9H-)-silafluorene) (V), thesynthesis of which is described, for example, by H. Gilman, R. D.Gorsich, J. Am. Chem. Soc. 1958, 80, 3243.

Compounds of the formula (IIIa) can be prepared, for example, startingfrom a tetrahalogenation in the 2,2′,7,7′ positions of9,9′-spirobi-9-silafluorene and a subsequent substitution reaction,which are known from analogous C-spiro compounds (see, for example, U.S.Pat. No. 5,026,894). This can lead, for example, by the correspondingcyano compounds, to aldehyde or carboxylic acid functionality which, canbe used, for example, for constructing heterocycles.

Compounds of the formula (IIIb) can be prepared, for example, by amethod similar to that for formula (IIIa), the stoichiometric ratios inthe reaction being chosen such that the 2,2′ and 7,7′ positions arefunctionalized (see, for example, J. H. Weisburger, E. K. Weisburger, F.E. Ray, J. Am. Chem. Soc. 1959, 72, 4253; F. K. Sutcliffe, H. M.Shahidi, D. Paterson, J. Soc. Dyers Colour 1978, 94, 306 and G. Haas, V.Prelog, Helv. Chim. Acta 1969, 52, 1202).

The compounds of the formula (IIIc) and (IIId) can be prepared, forexample, via a dibromination in the 7,7′-position of the2,2′-dicyano-9,9′-spirobi-9-silafluorene, synthesized by a methodsimilar to (IIIa), and subsequent reactions using a method similar tothat for compounds (IIIa).

Compounds of the formula (IIIe)-(IIIg) can be prepared, for example, bychoosing suitably substituted starting compounds for constructing thespirosilabifluorene, for example:

or:

It is also possible to use the synthesis sequences known to the personskilled in the art, for example nitration, reduction, diazotization andthe Sandmeyer reaction. For the synthesis of the K, L, M, N groups,reference may be made, for example, to DE-A 23 44 732, 24 50 088, 24 29093, 25 02 904, 26 36 684, 27 01 591 and 27 52 975 for compoundscontaining 1,4-phenylene groups; DE-A 26 41 724 for compounds containingpyrimidin-2,5-diyl groups; DE-A 40 26 223 and EP-A 03 91 203 forcompounds containing pyridin-2,5-diyl groups; DE-A 32 31 462 forcompounds containing pyridazin-3,6-diyl groups; N. Miyaura, T. Yanagiand A. Suzuki in Synthetic Communications 11 (1981) 513 to 519, DE-A-3930 663, M. J. Sharp, W. Cheng, V. Snieckus in Tetrahedron Letters 28(1987), 5093; G. W. Gray in J. Chem. Soc. Perkin Trans 11 (1989) 2041and Mol. Cryst. Liq. Cryst. 172 (1989) 165, Mol. Cryst. Liq. Cryst. 204(1991) 43 and 91; EP-A 0 449 015; WO 89/12039; WO 89/03821; EP-A 0 354434 for the direct linking of aromatics and heteroaromatics.

The preparation of disubstituted pyridines, disubstituted pyrazines,disubstituted pyrimidines and disubstituted pyridazines is given, forexample, in the appropriate volumes of the series “The Chemistry ofHeterocyclic Compounds” by A. Weissberger and E. C. Taylor (editors).

The spiro compounds described above exhibit an unusually markedfluorescence in the dissolved, finely distributed or solid state. Theyare used for the optical brightening of many different synthetic,semisynthetic or natural organic materials or substances which containorganic materials.

The invention thus further provides for the use of spiro compounds ofthe formulae (I) to (V) as optical brighteners.

The invention further provides a method of optical brightening whichcomprises adding to the material to be optically brightened one or morespiro compounds of the formulae (I) to (V).

Examples of groups of materials which are suitable for opticalbrightening are the following:

I. Synthetic, high-molecular-weight materials:

a) Polymerization products based on compounds containing at least onepolymerizable carbon-carbon double bond, i.e. their homo- or copolymersand their post-treatment products, such as, for example, crosslinking,graft or degradation products, polymer sections or products obtained bymodifying reactive groups, for example polymers based on unsaturatedcarboxylic acids or their derivatives, in particular acrylic compounds(such as acrylates, acrylic acid, acrylonitrile, acrylamides and theirderivatives or their methacrylic analogs), polymers of olefins (such as,for example, ethylene, propylene, styrenes or dienes, and also ABSpolymers), polymers based on vinyl and vinylidene compounds (such asvinyl chloride and vinyl alkcohol),

b) Polymerization products obtainable by ring opening, e.g. polyamidesof the polycaprolactam type, and also polymers obtainable either bypolyaddition or by polycondensation, such as polyethers or polyacetals,

c) Polycondensation products or precondensates based on bi- orpolyfunctional compounds containing condensable groups, their homo- andco-condensation products, and products of post-treatment, such as, forexample, polyesters, in particular saturated (e.g. ethylene glycolterephthalic acid polyesters) or unsaturated (e.g. maleic acid dialcoholpolycondensates and their crosslinking products with copolymerizablevinyl monomers), unbranched (including those based on polyhydricalcohols, such as alkyd resins) polyesters, polyamides (e.g.hexamethylenediamine adipate), maleic resins, melamine resins, theirprecondensates and analogs, polycarbonates, silicones,

d) Polyaddition products, such as polyurethanes (crosslinked andnoncrosslinked) and epoxy resins.

II. Semisynthetic materials, e.g. cellulose esters having varyingdegrees of esterification (e.g. so-called 2½ acetate, triacetate) orcellulose ethers, regenerated cellulose (viscose, cuprammonia cellulose)or their post-treatment products, or casein polymers.

Ill. Natural organic materials of an animal or vegetable origin, forexample those based on cellulose or proteins, such as cotton, wool,linen, silk, natural “coating resins”, starch, casein.

Preferred organic materials are those based on polyester, polyethylene,polypropylene, polystyrene, acrylic polymers, polyamide, polymethane,polyvinyl chloride, acetylcellulose, polyethylene terephthalate andengineering plastics, such as, for example, aramid fibers.

The organic materials which are to be optically brightened can belong tovery many different types of processing states (raw materials,semifinished products or finished products). On the one hand, they canbe in the form of very many differently shaped structures, for exampleas predominantly three-dimensional articles, such as plates, profiles,injection moldings, various workpieces, chips, granules or foammaterials, and also as predominantly two-dimensional articles, such asfilms, foils, surface coatings, impregnations and coverings, or aspredominantly one-dimensional articles, such as threads, fibers, flocksand wires. On the other hand, these materials can also be in an unshapedstate in very many different homogeneous or nonhomogeneous distributionforms, e.g. as powders, solutions, emulsions, dispersions, lattices,pastes or waxes.

The compounds which are to be used according to the invention areespecially important as optical brighteners for polymers, in particulartransparent polymers.

Fiber materials can, for example, be in the form of continuous threads(drawn or undrawn), staple fibers, flocs, strands, textile threads,yams, twisted yams, nonwovens, felts, waddings, floc structures or astextile fabrics or textile composites, knitted fabrics and also papers,cards or pulps.

Where fibers, which can be in the form of staple fibers or continuousfibers, in the form of threads, wovens, knits, nonwovens, flockedsubstrates or composites, are to be optically brightened according tothe invention, this is advantageously carried out in an aqueous medium,in which the compounds in question are present in finely dispersed form(suspensions, microdispersions, in some instances solutions). Whereappropriate, dispersants, stabilizers, wetting agents and otherauxiliaries can be added during the treatment.

Depending on the brightener compound type used, it may prove to beadvantageous to work in a neutral or alkaline or acidic liquor. Thetreatment is usually carried out at temperatures of from 20° C. to 140°C., for example at or around the boiling temperature of the liquor.Because of the outstanding temperature stability of the spiro compounds,it is also possible to choose liquor temperatures up to 400° C. For thefinishing of textile substrates according to the invention, solutions oremulsions in organic solvents are also suitable, as is the practice indyeing in so-called solvent dyeing (pad mangle heat setting application,exhaust dyeing method in dyeing machines).

According to the invention, the optical brighteners can, for example,also be used for brightening pulps, also in the presence of, forexample, cationic retaining agents and other additives.

The spiro compounds can also be added to or incorporated into thematerials before or during shaping. Thus, it is, for example, possibleto add them during the preparation of films, foils (e.g. rolling-in inpolyvinyl chloride at elevated temperature) or of molded articles of acompression molding material or injection molding composition. Aparticular advantage of the spiro compounds is that even higherprocessing temperatures (up to 400° C.) than those customarily usedhitherto can be used. In particular, this has opened up the possibilityof brightening engineering plastics which require higher processingtemperatures (e.g. aramid fibers).

Where the materials are shaped using spinning methods or by spinningdopes, the optical brighteners can be applied by the following methods:

addition to the starting substances (e.g. monomers) or intermediates(e.g. precondensates, prepolymers), i.e. before or duringpolymerization, polycondensation or polyaddition,

dusting on to polymerization chips or granules for spinning dopes,

liquor dyeing of polymerization chips or granules for spinning dopes,

metered addition to spinning melts or spinning solutions. As a result ofthe absolute stability to sodium rhodanide, the incorporation intospinning dopes for the preparation of polyacrylonitrile fibers in thewet spinning process based on rhodanide-containing spinning andprecipitation baths is of particular interest

application to tows prior to drawing.

According to the present invention, the optical brighteners can, forexample, be used in the following types of application:

a) mixtures or molecular dispersions containing polymers, preferablytransparent polymers, such as acrylates, methacrylates, carbonates,polyesters (e.g. PET), polyethers or epoxy resins,

b) mixtures containing dyes (nuancing) or pigments (colored or, inparticular, also white pigments) or as an additive to dyeing baths,printing, discharge or reserve pastes, and also for the post-treatmentof dyeings, prints or discharges,

c) in mixtures with carriers, wetting agents, plasticizers, swellingagents, antioxidants, antifungicides and antibactericides, lightprotection agents, heat stabilizers, chemical bleaches (for examplechlorite bleaches, hydrogen peroxide or peroxidic bleaches,percarboxylic acid bleaches, bleaching bath additives); the addition ofreducing compounds, for example, sulfur compounds, is important in thecase of types of spirobifluorene compounds. Particularly preferredcommercial forms are concentrated, aqueous solutions. The sulfurcompounds which have a reducing action can either be organic orinorganic in nature and are preferably water-soluble. Suitable examplesare dithionites, pyrosulfites, sulfites, sulfides, thiosulfates andthiocyanates (e.g. potassium rhodanide) in the form of their salts (e.g.alkali metal, alkaline earth metal or ammonium salts) as aqueoussolutions, in solid form or, as far as is known, also in the form of thefree acids or their anhydrides, such as sulfur dioxide. Examples oforganic compounds are mercaptans, such as thioglycolic acid,mercaptoethanol, 4-hydroxy-2-mercapto-3,3′-dithiodipropionic acid,sulfinates, such as sodium formaldehyde sulfoxylate orformamidinesulfinic acid and thiourea. Particular preference is given tosodium dithionite.

The amount of sulfur compound is generally 0.05-10 mol %, based on thebrightener, preferably 0.5-5 mol %,

d) in a mixture with crosslinkers, finishing agents (e.g. starch orsynthetic finishing agents) and in combination with many differenttextile finishing procedures, in particular synthetic-resin finishes(e.g. creaseproof finishes, such as “wash-and-wear”, “permanent-press”,“no-iron”), and also antistatic finishes or antimicrobial finishes,

e) incorporation of the optical brighteners into polymeric carriermaterials (polymerization, polycondensation or polyaddition products) indissolved or dispersed form for applications in coating, impregnation orbinding materials (solutions, dispersions, emulsions) for textiles,nonwovens, paper, leather,

f) as additives for “masterbatches”,

g) as additives for many different types of industrial products in orderto make them more salable (e.g. to improve the appearance of soaps,detergents, pigments, PET bottles, aramid fibers and sewing threads forsport articles, shoes, tear-resistant ropes, bulletproof vests, roofingfelt, disposable films),

h) in combination with other substances which have an opticallybrightening effect, in particular mixtures of optical brightenersconsisting of from 1 to 60% by weight of a brightener from the series ofbisbenzoxazolyl-substituted spirobifluorenes and from 99 to 40% byweight of one or more standard commercial brighteners, such as, forexample, brighteners from the series of coumarin, stilbene or pyrenebrighteners. Since some of the Spiro compounds produce brighteningeffects with a green shade, it is particularly advantageous to use themtogether with brighteners which produce reddish brightening effects(e.g. compounds from the class of 2-stilbenylnaphthotriazoles).Preference is also given to mixtures of spiro compounds, the optimummixing ratio depending in each case on the type of spiro compounds inquestion and being readily determinable by simple preliminaryexperiments.

In some cases, such mixtures can also result in unexpected synergisticeffects with respect to the brightness and the brilliance of thebrightenings,

i) in spinning bath preparations, i.e. as additives for spinning bathsas are used for improving slip for the further processing of syntheticfibers, or from a specific liquor prior to drawing the fibers,

j) as scintillators for various purposes of a photographic nature, e.g.for electrophotographic reproductions or supersensitization, for theoptical brightening of photographic layers.

For various reasons, it is often expedient to use the brightener not asit is, i.e. pure, but mixed with a variety of auxiliaries and subduingagents, such as anhydrous sodium sulfate, sodium sulfate decahydrate,sodium chloride, sodium carbonate, alkali metal phosphates, such assodium or potassium tripolyphosphates or alkali metal silicates.

In certain cases, the brighteners are fully activated by means of apost-treatment. This can, for example, be a chemical treatment (e.g.acid treatment), a thermal treatment (e.g. heat) or a combinedchemical/thermal treatment. An expedient way of carrying out the opticalbrightening of a series of fiber substances, e.g. of polyester fibers,using the brighteners thus involves impregnating these fibers withaqueous dispersions (where appropriate also solutions) of the brightenerat temperatures between 80° C. and room temperature and subjecting themto a dry heat treatment at temperatures above 100° C., it generallybeing advisable to dry the fiber material beforehand at moderatelyelevated temperature, e.g. at at least 60° C. to about 180° C. The heattreatment in the dry state is then advantageously carried out attemperatures between 120 and 225° C., for example by warming in a dryingchamber, by ironing in the given temperature range or by treating withdry, superheated steam. The drying and dry heat treatment can also becarried out directly after one another or be carried out together in asingle operation.

The amount of optical brightener to be used according to the invention,based on the material to be brightened, can vary within wide limits.Even using extremely small amounts, in certain cases e.g. amounts of10⁻⁶ percent by weight, it is possible to achieve a clear and lastingeffect. It is, however, also possible to use amounts up to about 3% byweight in some instances. For many practical requirements, amountsbetween 0.00001 and 0.5 percent by weight are preferably of interest.For some applications, for example as transformation material, inparticular in layered form, for UV light for increasing the efficiencyin solar cells, the amount of the novel brightener can also besignificantly higher (from 3 to 90% by weight, preferably from 10 to 75%by weight, particularly preferably from 10 to 50% by weight). Thecomponent(s) additionally used, preferably transparent polymers, inthese cases usually adopt(s) the role of a binder.

In this connection, it is particularly advantageous that at least thespiro compounds of the formula (I) can be mixed in any ratio with knownpolymers.

The spiro compounds are also suitable as additives for wash baths or forindustrial and domestic detergents, in particular also for concentrated,liquid or solid detergents. For wash baths, the brighteners areexpediently added in the form of their solutions in water or organicsolvents or else in fine distribution as aqueous dispersions. Fordomestic or industrial detergents, they are advantageously used in anyphase of the preparation process of the detergent, e.g. the “slurry”,prior to atomization. They can be added either in the form of a solutionor dispersion in water or other solvents or else without auxiliaries asa dry brightener powder. It is possible, for example, to mix, knead orgrind the brightener with the detersive substances, and add it in thisform to the finished detergent powder. They can, however, also besprayed onto the finished detergent in dissolved or predispersed form.

Suitable detergents are the known mixtures of detersive substances, suchas, for example, soaps in the form of chips and powders, synthetics,soluble salts of sulfonic half-esters of higher fatty alcohols, higherand/or alkyl-polysubstituted arylsulfonic acids, sulfocarboxylates ofmedium to higher alcohols, fatty acid acylaminoalkyl- or -aminoarylglycerol sulfonates, phosphonates of fatty alcohols etc., and alsocustomary surfactants, for example the water-soluble products obtainedfrom the addition of an, alkylene oxide or an equivalent compound with areactive hydrogen atom of a hydrophobic compound. The hydrophobicorganic products can be heterocycles and particularly aliphatics oraromatics. Preference is given to higher aliphatic alcohols andalkylphenols, although others, e.g. carboxylic acids, carboxamides,mercaptans and sulfamides, can also be used. Preferred nonionogeniccompounds are the addition products of ethylene oxide with higheraliphatic alcohols having from 6 to 50 and above carbon atoms. Theamount of ethylene oxide can vary within wide limits, but at least 5 molof ethylene oxide are generally consumed per mole of hydrophobicsubstance. Instead of some or all of the ethylene oxide, it is possibleto use other lower alkylene oxides, for example propylene oxide andbutylene oxide.

Examples of other suitable nonionogenic surfactants are:

a) polyoxyalkylene esters of organic acids, such as higher fatty acids,resin acids, tallow oil acids and acids of the oxidation products ofpetroleum, the esters of which usually have from 10 to 22 carbon atomsin the acid moiety and contain from about 12 to about 30 moles ofethylene oxide or its equivalent.

b) alkylene oxide adducts of higher fatty acid amides, the fatty acidmoiety generally having from 8 to 22 carbon atoms and being condensedwith from 10 to 50 mol of ethylene oxide. The corresponding carboxamidesand sulfamides can likewise be used.

In the preparation of concentrated detergents, the nonionogenicsurfactants used are preferably oxalkylated higher aliphatic alcohols,the fatty alcohols having at least 6, and preferably at least 8, carbonatoms. Preferred alcohols are lauryl, myristyl, cetyl, stearyl and oleylalcohol, which are condensed with at least 6 mol of ethylene oxide. Atypical nonionogenic product is the addition product of an aliphaticalcohol having 12-13 carbon atoms with about 6.5 mol of ethylene oxide.The corresponding alkylmercaptans can, following condensation withethylene oxide, likewise be used as nonionogenic surfactants.

The alkoxylated higher alcohols are particularly suitable for domesticdetergents since they are readily biodegradable and are readilycompatible with cationic surfactants and textile softeners and customaryadditives.

Examples of suitable builders are alkali metal poly- andpolymetaphosphates, alkali metal pyrophosphates, alkali metal salts ofcarboxymethylcellulose and other “soil redeposition inhibitors”, andalso alkali metal silicates, alkali metal carbonates, alkali metalborates, alkali metal perborate, nitrilotriacetic acid,ethylenediaminotetraacetic acid, foam stabilizers, such as alkanolamidesof higher fatty acids. The detergents may additionally comprise, forexample: antistatics, refatting skin protectants, such as lanolin,enzymes, antimicrobial substances, perfumes, dyes and cationic textilesofteners.

Suitable cationic textile softeners are especially quaternaryderivatives of ammonia and/or of imidazoline having 2 long-chain,aliphatic saturated or unsaturated radicals.

Examples of quatemary ammonium softeners are: tallyltrimethylammoniumchloride, ditallyldimethylammonium chloride; ditallyldimethylammoniumsulfate, dihexadecyldimethylammonium chloride;dioctadecyldimethylammonium chloride, dieicosyldimethylammoniumchloride, didocosyldimethylammonium chloride, dihexadecyidiethylammoniumchloride, dihexadecylmethylammonium acetate, ditallyldipropylammoniumphosphate, ditallyldimethylammonium nitrate, dicocoyldimethammoniumchloride, 1-methyl-1-stearylamidoethyl-2-heptadecylimidazoliniummethosulfate, 1-methyl-1-palmitoylamidoethyl-2-octadecylimidazoliniumchloride, 2-tallyl-1-methyl-1-talloylamidoethylimidazoliniummethosulfate.

Further examples of suitable textile softeners are:1-methyl-1-oleylamidoethyl-2-octadecylimidazolinium chloride,1-methyl-1-talloylamidoethyl-2-tallylimidazolinium chloride,ditallyldimethylammonium chloride,1-methyl-1-oleylamidoethyl-2-oleylimidazolinium methosulfate,1-methyl-1-talloylamidoethyl-2-tallylimidazolinium methosulfate.

The spiro compounds have the particular advantage that they are alsoeffective in the presence of active-chlorine donors, such ashypochlorite, and can be used without considerable losses in the effectsin wash baths containing nonionogenic detergents, e.g. alkylphenolpolyglycol ethers.

The spiro compounds are added in amounts of 0.00001-1% or above, basedon the weight of the liquid or pulverulent, finished detergent. Washliquors which contain the given amounts of claimed optical brightenersimpart a brilliant appearance in daylight in the washing of textilesmade from cellulose fibers, polyamide fibers, resin-finished cellulosefibers, polyester fibers, wool etc.

The washing treatment is, for example carried out as follows:

Said textiles are treated for from 1 to 30 minutes at from 20 to 100° C.in a washing bath which comprises from 1 to 10 g/kg of a compounddetergent containing a builder and from 0.0005 to 1%, based on thedetergent weight, of the claimed brightener. The liquor ratio can befrom 3:1 to 50:1. After washing, rinsing and drying is carried out asusual. The wash bath can contain, as bleach additive, 0.2 g/l of activechlorine (e.g. hypochlorite) or from 0.1 to 2 g/l of sodium perborate.

The spiro compounds can also be used in the after-rinse bath, as iscustomary for merely imparting softness, antistatic properties, antisoileffects, perfume notes etc. In particular, they are suitable for use inlaundry post-treatment compositions which contain cationic softeners.

EXAMPLES A. Starting compounds

a) Synthesis of 9,9′-spirobifluorene

6.3 g of magnesium turnings and 50 mg of anthracene were introducedunder argon into 120 ml of dry diethyl ether in a 1 I three-neck flaskfitted with a reflux condenser, and the magnesium was activated for 15min using ultrasound. 62 g of 2-bromobiphenyl were dissolved in 60 ml ofdry diethyl ether. Approximately 10 ml of this solution were added tothe initial charge of magnesium in order to start the Grignard reaction.

After the reaction had started, the 2-bromobiphenyl solution was addeddropwise with further ultrasound treatment at a rate such that thesolution was gently refluxed. When addition was complete, the reactionmixture was refluxed with ultrasound for a further hour.

48.8 g of 9-fluorenone were dissolved in 400 ml of dry diethyl ether andadded dropwise with further ultrasound treatment to the Grignardsolution. When addition was complete, the mixture was boiled for afurther 2 h. The yellow magnesium complex of 9-(2-biphenyl)-9-fluorenolwhich precipitated out when the reaction mixture was cooled was filteredoff with suction and washed with a small amount of ether. The magnesiumcomplex was hydrolyzed in 800 ml of iced water which contained 40 g ofammonium chloride. After the mixture had been stirred for 60 min, the9-(2-biphenyl)-9-fluorenol formed was filtered off with suction, washedwith water and sucked dry.

The dried 9-(2-biphenyl)-9-fluorenol was then dissolved in 500 ml ofglacial acetic acid at elevated temperature. 0.5 ml of conc.hydrochloric acid was added to this solution. The solution was allowedto boil for a few minutes, and the 9,9′-spirobifluorene which formed wasprecipitated out of the hot solution with water (addition of water untilthe onset of turbidity). After cooling, the product was filtered offwith suction and washed with water. The dried product was recrystallizedfrom ethanol in order to purify it further. This gave 66 g (80%, basedon 2-bromobiphenyl) of 9,9′-spirobifluorene as colorless crystals, m.p.198° C.

b) 2,2′-Dibromo-9,9′-spirobifluorene (F. K. Sutcliffe, H. M. Shahidi, D.Patterson, J. Soc. Dyers Colour 94 (1978) 306)

3.26 g (10.3 mmol) of 9,9′-spirobifluorene were dissolved in 30 ml ofmethylene chloride, and 5 mg of FeCl₃ (anhydrous) were added thereto ascatalyst. The reaction flask was protected from the entry of light. 1.12ml (21.8 mmol) of bromine in 5 ml of methylene chloride were addeddropwise with stirring over the course of 30 min. After 24 h, theresulting brown solution was washed with saturated, aqueous NaHCO₃solution and water in order to remove excess bromine. After drying overNa₂SO₄, the organic phase was concentrated by. evaporation on a rotaryevaporator. The white residue was recrystallized from methanol to give3.45 g (70%) of the dibromo compound as colorless crystals, m.p. 240° C.

c) 2,2′,7,7′-Tetrabromo-9,9′-spirobifluorene

80 mg (0.5 mmol) of anhydrous FeCl₃ were added to a solution of 3.16 g(10.0 mmol) of 9,9′-spirobifluorene in 30 ml of methylene chloride, and2.1 ml (41 mmol) of bromine in 5 ml of methylene chloride were addeddropwise over 10 min. The solution was refluxed for 6 h. Upon cooling,the product precipitated out. The precipitate was filtered off withsuction and washed with a small amount of cold methylene chloride.Drying gave 6.0 g (95%) of the tetrabromo compound as a white solid.

d) 2-Bromo-9,9′-spirobifluorene and 2,2′,7-tribromo-9,9′-spirobifluorenewere prepared in an analogous manner with modified stoichiometry.

e) 9,9′-Spirobifluorene-2,2′-dicarboxylic acid from2,2′-dibromo-9,9′-spirobifluorene via 2,2′-dicyano-9,9′-spirobifluorene

1.19 g of 2,2′-dibromo-9,9′-spirobifluorene and 0.54 g of CuCN wererefluxed in 5 ml of DMF for 6 h. The resulting brown mixture was pouredinto a mixture of 3 g of FeCI₃ (hydrat.) and 1.5 ml of conc.hydrochloric acid in 20 ml of water. The mixture was held at from 60 to70° C. for 30 min in order to destroy the Cu complex. The hot aqueoussolution was extracted twice with toluene. The organic phases were thenwashed with dilute hydrochloric acid, water and 10% strength aqeuousNaOH. The organic phase was filtered and concentrated by evaporation.The resulting yellow residue was recrystallized from methanol. This gave0.72 g (80%) of 2,2′-dicyano-9,9′-spirobifluorene as pale yellowishcrystals (melting range 215 to 245° C.).

3 g of 2,2′-dicyano-9,9′-spirobifluorene were refluxed with 25 ml of 30%strength aqueous NaOH and 30 ml of ethanol for 6 h. The disodium salt ofspirobifluorenedicarboxylic acid precipitated out as a yellowpreipitate, which was filtered off and heated in 25% strength aqueousHCl in order to obtain the free acid. The spirobifluoremedicarboxylicacid was recrystallized from glacial acetic acid. This gave 2.2 g(66.6%) of white crystals (m.p. 376° C., IR band 1685 cm⁻¹ C═O).

9,9′-Spirobifluorene-2,2′,7,7′-tetracarboxylic acid was prepared from2,2′,7,7′-tetrabromo-9,9′-spirobifluorene in an analogous manner.

f) 9,9-Spirobifluorene-2,2 ′-dicarboxylic acid from 9,9′-spirofluorenevia 2,2′-diacetyl-9,9′-spirobifluorene (G. Haas, V. Prelog, Helv. Chim.Acta 52 (1969) 1202; V. Prelog, D. Bedekovic, Helv. Chim. Acta 62 (1979)2285)

9.0 g of finely powdered, anhydrous AlCl₃ were added to a solution of3.17 g of 9,9′-spirobifluorene in 30 ml of abs. carbon disulfide, andthen 1.58 g of acetyl chloride in 5 ml of abs. carbon disulfide wereadded dropwise over the course of 10 min with stirring, and the mixturewas then refluxed for 1 hour. 100 g of ice and 50 ml of 2n hydrochloricacid were added at 0° C. to the mixture which had been evaporated todryness under reduced pressure. After customary work-up, the crudeproduct was separated by chromatography using benzene/ethyl acetate(10:1) on silica gel. This gave 3.62 g (89%) of2,2′-diacetyl-9,9′-spirobifluorene (recrystallized from chloroform/ethylacetate, m.p. 255 to 257° C.) and 204 mg of2-acetyl-9,9′-spirobifluorene (recrystallized from chloroforan/benzene,m.p. 225° C.). [in addition, in the chromatography,2,2′,7-triacetyl-9,9′-spirobifluorene (m.p. 258 to 260° C.) and2,2′,7,7′-tetraacetyl-9,9′-spirobifluorene (m.p. >300° C.) were alsoisolated, recrystallized from ethyl acetate/hexane].

2,2′,7-Triacetyl- and 2,2′,7,7′-tetraacetyl-9,9′-spirobifluorene wereobtained with modified stoichiometry as the main product.

At 0° C., first 7.2 g of bromine and then a solution of 3.0 g of2,2′-diacetyl-9,9′-spirobifluorene in a small amount of dioxane wereadded dropwise with stirring to a solution of 6.0 g of sodium hydroxidein 30 ml of water. After the mixture had been stirred for a further 1hour at room temperature, 1 g of sodium hydrogensulfite, dissolved in 20ml of water, was added to the clear yellow solution. Followingacidification with conc. hydrochloric acid, the colorless product whichhad precipitated out was filtered off and washed with a small amount ofwater. Recrystallization from ethanol produced9,9′-spirobifluorene-2,2′-dicarboxylic acid as water-clear prisms (m.p.352° C.).

9,9′-Spirobifluorene-2-carboxylic acid,9,9′-spirobifluorene-2,2′,7-tricarboxylic acid and9,9′-spirobifluorene-2,2′,7,7′-tetracarboxylic acid were prepared in ananalogous manner.

g) 2,2′-Bis(bromomethyl)-9,9′-spirobifluorene from2,2′-dicarboxy-9,9′-spirobifluorene via9,9′-spirobifluorene-2,2′-dimethanol (V. Prelog, D. Bedekovicc, Helv.Chim. Acta 62 (1979) 2285)

At room temperature, 10 g of a 70% by weight strength solution of sodiumdihydro-bis(2-methoxyethoxy)aluminate (Fluka) in benzene were slowlyadded dropwise to a suspension of 2.0 g of2,2′-dicarboxy-9,9′-spirobifluorene (free carboxylic acid) in 20 ml ofbenzene. After the mixture had been refluxed for 2 h, during which timethe carboxylic acid dissolved, the excess reducing agent was decomposedat 10° C. using water, the mixture was acidified using conc.hydrochloric acid and extracted by shaking with chloroform.

The organic phase was washed with water, dried over magnesium sulfateand evaporated, and the residue was recrystallized from benzene. Thisgave 1.57 g of 9,9′-spirobifluorene-2,2′-dimethanol (m.p. 254 to 255°C.). 91.5 g of 33% strength aqueous solution of hydrogen bromide inglacial acetic acid were added dropwise to a solution of 13.5 g of9,9′-spirofluorene-2,2′-dimethanol in 400 ml of benzene, and the mixturewas refluxed for 7 h. 200 ml of water were then added, and the organicphase was washed with water, dried with magnesium sulfate andevaporated. Chromatography on silica gel using benzene produced 11.7 gof 2,2′-bis(bromomethyl)-9,9′-spirobifluorene as colorless flakes (m.p.175 to 177° C.).

h) 5 g of chromium(VI) oxide on graphite (Seloxcette, Alpha Inorganics)were added to a solution of 380 mg of9,9′-spirobifluorene-2,2′-dimethanol in 15 ml of toluene, and themixture was refluxed under nitrogen for 48 h. The mixture was thenfiltered with suction using a glass suction filter, and the filtrate wasevaporated. Chromatography on silica gel using chloroform andcrystallization from methylene chloride/ether produced 152 mg of9,9′-spirobifluorene-2,2′-dicarbaldehyde (m.p. >300° C.) and 204 mg of2′-hydroxymethyl-9,9′-spirobifluorene-2-carbaldehyde (m.p. 262 to 263°C.).

i) 2,2′-Diamino-9,9′-spirobifluorene

A mixture of 150 ml of conc. aqueous HNO₃ and 150 ml of glacial aceticacid were added dropwise to a boiling solution of 15.1 g of9,9′-spirobifluorene in 500 ml of glacial acetic acid over a period of30 min, and then the solution was refluxed for a further 75 min. Afterthe solution had cooled and been allowed to stand for 1 hour, the samevolume of water was added, resulting in precipitation of the product.Filtration with suction gave 18.5 g of yellow crystals (m.p. 220 to 224°C.) of 2,2′-dinitro-9,9′-spirobifluorene. Recrystallization from 250 mlof glacial acetic acid gave 12.7 g of pale yellow crystal needles (m.p.245 to 249° C., analytically pure 249 to 250° C.).

A mixture of 4.0 ml of dinitrospirobifluorene and 4.0 g of iron powderwere refluxed in 100 ml of ethanol, while 15 ml of conc. HCl were addeddropwise over a period of 30 min. After the mixture had been refluxedfor a further 30 min, excess iron was filtered off. The green filtratewas introduced into a solution of 400 ml of water, 15 ml of conc. NH₄OHand 20 g of Na,K tartrate. The white diamine was filtered off from thedark green solution of the iron complex. The diamine was purified bydissolving it in dilute HCl and, at room temperature, stirring it withactivated carbon (Darco) and filtering. The filtered solution wasneutralized with NH₄OH dropwise with stirring (precision-ground glassstirrer), and the product which precipitated out was filtered off withsuction. This gave 3.5 g of white 2,2′-diamino-9,9′-spirobifluorene,which was recrystallized from ethanol (m.p. 243° C.).

j) Synthesis of 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene by brominationof solid 9,9′-spirobifluorene using bromine vapor.

3.16 g (10 mmol) of finely powdered 9,9′-spirobifluorene were introducedinto a flat porcelain evaporating dish (φ about 15 cm). This dish wasplaced in a desiccator (φ about 30 cm) on the perforated false bottom.15.6 g (4.8 ml, 96 mmol) of bromine in a crystallizing dish were placedon the floor of the desiccator. The desiccator was sealed, although theaeration cock was opened so that the HBr which formed was able toescape. The desiccator was placed overnight in a fume cupboard. On thenext day, the porcelain dish containing the product, which had beenturned orange in color by the bromine, was removed from the desiccatorand left to stand in the fume cupboard for at least a further 4 h sothat excess bromine and HBr could escape.

The product was dissolved in 150 ml of dichloromethane and washed with,in each case, 50 ml of sodium sulfite solution (saturated), sodiumhydrogencarbonate solution (saturated) and water until colorless. Thedichloromethane solution was dried over sodium sulfate and concentratedby evaporation on the rotary evaporator. The product was purified byrecrystallizing it from a 4:1 dichloromethane/pentane mixture. Yield 5.7g (92%) of colorless crystals.

¹H-NMR (CDCl₃, ppm): 6.83 (d, J=1.83 Hz, 4H, H-1,1′,8,8′); 7.54 (dd,J=7.93,1.83 Hz, 4H, H-3,3′,6,6′); 7.68 (d, J=7.93 Hz, 4H, H-4,4′,5,5′).

k) Synthesis of 2,2′,4,4′,7,7′-hexabromo-9,9′-spirobifluorene

200 mg of anhydrous FeCl₃ were added to a solution of 3.16 g (10 mmol)of 9,9′-spirobifluorene in 20 ml of methylene chloride, and the mixturewas treated with ultrasound. The reaction flask was protected againstthe entry of light using Al foil. 9.85 g (3.15 ml, 62 mmol) of brominein 5 ml of methylene chloride were then added dropwise at the boil overthe course of 15 min. The solution was refluxed for a further 20 h andtreated with ultrasound. After cooling, petroleum ether is added and themixture is filtered with suction. The product is further purified byrecrystallizing it from THF/methanol, and drying it for 5 h at 80° C.

Yield 6.15 g (77%) of colorless crystals.

¹H-NMR (CDCl₃, ppm): 6.76 (d, J=1.53 Hz, 2H, H-1,1); 6.84 (d, J=1.83 Hz,2H, H-8,8); 7.60 (dd, J=8.54,1.83 Hz, 2H, H-6,6′); 7.75 (d, J=1.53 Hz,2H, H-3,3′); 8.49 (d, J=8.54Hz, 2H, H-5,5′).

I) Synthesis of 2,7-dibromo-9,9′-spirobifluorene

A Grignard reagent prepared from 0.72 g (30 mmol) of magnesium turningsand 5.1 ml (30 mmol) of 2-bromobiphenyl in 15 ml of diethyl ether wasadded dropwise to a boiling suspension of 10.0 g (29.6 mmol) of2,7-dibromo-9-fluorenone in 100 ml of dry diethyl ether with stirring(in an ultrasound bath) over the course of 2 h. When addition iscomplete, the mixture is boiled for a further 3 hours. After coolingovernight, the precipitate which had formed was filtered off withsuction and washed with cold ether. The magnesium complex which had beenfiltered off with suction was hydrolyzed in a solution of 15 g ofammonium chloride in 250 ml of iced water. After 1 h, the9-(2-biphenylyl)-2,7-dibromo-9-fluorenol which formed was filtered offwith suction, washed with water and was sucked dry. For the ring-closurereaction, the dried fluorenol was boiled for 6 hours in 100 ml ofglacial acetic acid, after the additon of 3 drops of conc. HCl. Themixture was left to crystallize overnight, and the product which formedwas filtered off with suction and washed with glacial acetic acid andwater.

Yield: 11 g (77%) of 2,7-dibromo-9,9′-spirobifluorene. The product wasfurther purified by recrystallizing it from THF.

¹H-NMR (CDCl₃, ppm): 6.73 (d, J=7.63 Hz, 2H, H-1′,8′); 6.84 (d, J=1.83Hz, 2H, H-1,8); 7.15 (td, J=7.63, 1.22Hz., 2H, H-2′,7′); 7.41 (td,J=7.63, 1.22 Hz, 2H, H-3′,6′); 7.48 (dd, J=8.24,1.83 Hz, 2H, H-3,6);7.67 (d, J=8.24; 2H; H-4,5); 7.85 (d, J=7.63, 2H, H-4′,5′).

m) Synthesis of 2,7-dicarbethoxy-9,9′-spirobifluorene

A Grignard reagent prepared from 0.97 g (40 mmol) of magnesium turningsand 9.32 g (6.8 ml, 40 mmol) of 2-bromobiphenyl in 50 ml of dry diethylether was added dropwise to a boiling solution of 13 g (40 mmol) of2,7-dicarbethoxy-9-fluorenone in 100 ml of dry diethyl ether over thecourse of 2 h. When addition was complete, the mixture was boiled for afurther 3 hours. After cooling overnight, the precipitate formed wasfiltered off with suction and washed with cold ether. The magnesiumcomplex was filtered off with suction and hydrolyzed in a solution of 15g of ammonium chloride in 250 ml of iced water. After 1 h, the9-(2-biphenylyl)-2,7-dicarbethoxy-9-fluorenol which had formed wasfiltered off with suction, washed with water and sucked dry. For thering-closure reaction, the dried fluorenol was boiled for 6 hours in 100ml of glacial acetic acid, following the addition of 3 drops of conc.HCl. The mixture was left to crystallize overnight, and the productwhich had formed was filtered off with suction and washed with glacialacetic acid and water.

Yield: 15.1 g (82%) of 2,7-dicarbethoxy-9,9′-spirobifluorene. Theproduct was further purified by recrystallizing it from ethanol.

¹H-NMR (CDCl₃, ppm): 1.30 (t, J=7.12Hz, 6 H, ester-CH₃); 4.27 (q, J=7.12Hz, 4H, ester-CH₂); 6.68 (d, J=7.63 Hz, 2H, H-1′,8′); 7.11 (td, J=7.48,1.22 Hz, 2H, H-2′,7′); 7.40 (td, J=7.48, 1.22Hz, 4H, H-1, 8, 3′,6′);7.89 (dt, J=7.63, 0.92Hz, 2H, H-4′,5′); 7.94 (dd, J=7.93, 0.6 Hz, 2H,H-4, 5); 8.12 (dd, J=7.93,1.53 Hz, 2H, H-3, 6).

n) Synthesis of 2,7-dibromo-2′,7′-diiodo-9,9′-spirobifluorene

At 80° C., 5 ml of water were added to a suspension of 2.37 g of2,7-dibromo-9,9′-spirobifluorene in 50 ml of glacial acetic acid in a250 ml three-neck flask fitted with a reflux condenser and droppingfunnel, and, after the addition of 2 ml of conc. sulfuric acid, 1.27 gof iodine, 0.53 g of iodic acid and 5 ml of carbon tetrachloride, themixture was stirred until the color of the iodine disappeared. Themixture was then filtered with suction and washed well with water. Afterdrying, the precipitate was dissolved in 150 ml of dichloromethane, andwashed successively with Na₂SO₃ solution, NaHCO₃ solution and withwater. The dichloromethane phase was dried over Na₂SO₄ and thenevaporated. This gave colorless crystals of2,7-dibromo-2′,7′-diiodo-9,9′-spirobifluorene in quantitative yield. Theproduct was further purified by recrystallizing it fromdichloromethane/pentane.

¹H-NMR (CHCl₃, ppm): 6.80 (d, J=1.83 Hz, 2H), 6.99 (d, J=1.53 Hz, 2H),7.51 (dd, J=8.24, 1.83 Hz, 2H), 7.54 (d, J=7.93 Hz, 2H), 7.65 (d,J=8.24Hz, 2H), 7.72 (dd, J=8.24, 1.53 Hz, 2H).

B. Synthesis examples

Example 1

2,2′-Bis(benzofuran-2-yl)-9,9′-spirobifluorene (by a method similar toW. Sahm, E. Schinzel, P. Jurges, Liebigs Ann.Chem. (1974) 523.)

2.7 g (22 mmol) of salicylaldehyde and 5.0 g (10 mmol) of2,2′-bis(bromomethyl)-9,9′-spirobifluorene were dissolved in 15 ml ofDMF at room temperature, and 0.9 g (22.5 mmol) of pulverized NaOH and aspatula tip of Kl were added thereto. The mixture was heated to boilingand stirred for 1 h at the boiling temperature. After cooling, a mixtureof 0.5 ml of conc. hydrochloric acid, 7 ml of water and 7 ml of methanolwere added to the reaction solution. The stirring was continued at roomtemperature for a further 1 h, the crystalline reaction products werefiltered off with suction, washed firstly with cold methanol, then withwater and dried under reduced pressure at 60° C. This gave 4.6 g (79%)of the bisbenzyl phenyl ether.

2.1 g (22.5 mmol) of freshly distilled aniline were added to 5.85 g (10mmol) of the bisbenzyl phenyl ether in 10 ml of toluene. A spatula tipof p-toluenesulfonic acid was added, and the mixture was heated toboiling at the water separator until water no longer separated off(about 3 to 5 h). As the reaction mixture cooled, the correspondingbisbenzylidenephenylamine crystallized out. The latter is filtered offwith suction, washed with methanol and dried at 60° C. under reducedpressure. It was further purified by recrystallizing it from DMF.

7.35 g (10 mmol) of the bisbenzylidenephenylamine and 0.62 g (11 mmol)of KOH were introduced under nitrogen into 30 ml of DMF. The mixture isthen heated with stirring at 100° C. for 4 h. After cooling to roomtemperature, the precipitate was filtered off with suction and washedwith a small amount of DMF and water. After drying at 60° C. in a vacuumdrying cabinet, the 2,2′-bis(benzofuran-2-yl)-9,9′-spirobifluorene waspurified by recrystallization from methyl benzoate.

Example 2

2,2′,7,7′-Tetra(benzofuran-2-yl)-9,9′-spirobifluorene was prepared witha correspondingly modified stoichiometry as in Example 1.

Example 3

2,2′,7,7′-Tetraphenyl-9,9′-spirobifluorene

5 g (7.9 mmol) of 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene, 3.86 g(31.6 mmol) of phenylboronic acid, 331.5 mg (1.264 mmol) oftriphenylphosphane and 70.9 mg (0.316 mmol) of palladium acetate wereslurried in a mixture of 65 ml of toluene and 40 ml of aqueous sodiumcarbonate solution (2 M). The mixture was refluxed for 24 h withvigorous stirring. After cooling to room temperature, the mixture wasfiltered with suction, washed with water and dried at 50° C. underreduced pressure. This gave 2.58 g of product. The filtrate wasextracted with 50 ml of toluene, and the dried organic phase wasevaporated to dryness. This gave a further 1.67 g of product. Overallyield 4.25 g (86%)

Example 4

Synthesis of 2,2′,7,7′-tetrakis(biphenyl-4-yl)-9,9′-spirobifluorene

5.5 g of tetrabromospirobifluorene, 7.2 g of biphenylboronic acid and400 mg of tetrakis(triphenylphosphine)palladium were slurried in amixture of 100 ml of toluene and 50 ml of potassium carbonate solutionin a 250 ml two-neck flask fitted with a reflux condenser andprecision-ground glass stirrer. The mixture was refluxed for 8 h withstirring using a precision-ground glass stirrer and with protective-gasblanketing. After cooling, the product was filtered off with suction,and the precipitate was washed with water and dried. In the filtrate,the toluene phase was separated off, and the aqueous phase was extractedby shaking once with chloroform. The combined organic phases were driedover sodium sulfate and concentrated by evaporation on a rotaryevaporator; this gave a second fraction of the product. The two productfractions were combined (8 g) and dissolved in chloroform. Thechloroform solution was boiled with activated carbon and filteredthrough a short column containing silica gel. Concentration byevaporation on a rotary evaporator and recrystallization fromchloroform/pentane gave colorless crystals which had a blue fluorescencein UV light.

Melting point 408° C. (DSC).

¹H-NMR (CDCl₃, ppm): 7.14 (d, J=1.53 Hz, 4H); 7.75 (dd, J=7.93,1.53 Hz,4H); 8.01 (d, J=7.93 Hz, 4H); 7.34 (dd, J=7.32, 1.37 Hz, 4H); 7.42 (t,J=7.32Hz, 8H); 7.58 (24H).

Example 5

Synthesis of 2,2′,4,4′,7,7′-hexakis(biphenyl-4-yl)-9,9-spirobifluorene

1.6 g of hexabromospirofluorene and 3 g of biphenylboronic acid wereslurried in a mixture of 50 ml of toluene and 50 ml of 1 M potassiumcarbonate solution in a 250 ml two-neck flask fitted with a refluxcondenser and precision-ground glass stirrer. The mixture was refluxedunder nitrogen, and 115 mg of tetrakis(triphenylphosphine)palladium in 5ml of toluene were added. The mixture was refluxed with stirring for 7h. When the reaction was complete, the cooled solution was filtered, andthe filtrate was extracted by shaking twice with water (to achievebetter phase separation, chloroform was added). The organic phase wasdried over sodium sulfate, filtered through a short column containingsilica gel and then concentrated by evaporation. It was further purifiedby recrystallizing it from dichloromethane/pentane. This gave 2 g (80%)of colorless crystals which have a blue fluorescence in UV light.

¹³C-NMR [360 MHz.; ATP, broad-band decoupled] (CDCl₃, ppm): 65.94 (1C,spiro-C); 126.95 (6C, CH), 126.97 (6C, CH), 127.17 (6C, CH), 127.35 (6C,CH), 127.36 (6C, CH), 127.39 (6C, CH), 127.52 (6C, CH), 128.73 (6C, CH),128.75 (6C, CH), 128.94 (6C, CH), 129.90 (4C, CH), 137.77 (2C), 137.86(2C), 139.43 (2C), 139.69 (2C), 139.89 (2C), 140.09 (2C), 140.17 (2C),140.22 (2C), 140.30 (2C), 140.63 (2C), 140.64 (2C), 140.68 (2C), 140.72(2C), 140.74 (2C), 150.45 (2C), 150.92 (2C).

Example 6

Synthesis of2,2′-bis[(5(p-t-butylphenyl)-1,3,4-oxadiazol-2yl]-9,9′-spirobifluorenefrom 9,9′-spirobifluorene-2,2′-dicarbonyl chloride and5(4-t-butylphenyl)tetrazole

a) Synthesis of 5(4-t-butylphenyl)tetrazole

4.99 of p-t-butylbenzonitrile, 3.82 g of lithium chloride and 5.85 g ofsodium azide and 8.2 g of triethylammonium bromide in 100 ml of DMF wereheated at 120° C. for 8 h in a 250 ml round-bottom flask fitted with areflux condenser. After cooling to room temperature, 100 ml of waterwere added, and, in an ice bath, dilute hydrochloric acid was addeduntil no more precipitate formed. The mixture was filtered with suction,and the precipitate was washed with water and dried. Recrystallizationfrom ethanol/water produced 4.4 g of colorless crystals.

b) 9,9′-Spirobifluorene-2,2′-dicarbonyl chloride

2 g (5 mmol) of 9,9′-spirobifluorene-2,2′-dicarboxylic acid wererefluxed with 20 ml of (freshly distilled) thionyl chloride and 3 dropsof DMF for 4 h in a 100 ml flask fitted with a reflux condenser anddrying tube. After cooling, the reflux condenser was exchanged for adistillation bridge, and excess thionyl chloride was distilled off underreduced pressure; 40 ml of petroleum ether (30°-60° C.) were added tothe residue, which was distilled off to leave the crystalline acidchloride.

c)2,2′-Bis[(5(p-t-butylphenyl)-1,3,4-oxadiazol-2yl]-9,9′-spirobifluorene

2.0 g (11 mmol) of 5(4-t-butylphenyl)tetrazole dissolved in 20 ml ofanhydrous pyridine were added to the acid chloride, and the mixture wasrefluxed for 2 h under protective gas. After cooling, the mixture wasintroduced into 200 ml of water and left to stand for 2 h. Theoxadiazole derivative which precipitated out was filtered off withsuction, washed with water and dried under reduced pressure. It was thenchromatographed over silica gel using chloroform/ethyl acetate (99:1),and recrystallized from chloroform/pentane. This gave 2.4 g of colorlesscrystals.

¹H-NMR (CDCl₃), ppm):

1.31 (s, 18H, t-butyl), 6.77 (d, J=7.32Hz, 2H), 7.18 (td, J=7.48,1.22Hz, 2H), 7.44 (td, J=7.40, 1.22Hz, 2H), 7.46 (d, J=8.54Hz, 4H), 7.50(d, J=1.22Hz, 2H), 7.94 (d, J=8.54Hz, 4H), 8.02 (d, J=7.93 Hz, 6H), 8.20(dd, J=7.93, 1.53 Hz, 2H).

C. Application examples Example 1

100 parts of polyester granules of ethylene glycol polyterephthalatewere intimately mixed with 0.05 parts of the compound of the formula (A)and melted at 285° C. with stirring.

Spinning the spinning dope using customary spinnerets gave greatlybrightened polyester fibers. The use of a compound of the formula (B) or(C) instead of the compound of the formula (A) produced similar results.

Example 2

A polyester fabric (“Dacron”) was formulated at room temperature usingan aqueous dispersion which comprised, per liter, 2 g of the compoundsof the formula (B) and 1 g of an addition product of about 8 mol ofethylene oxide with 1 mol of p-tert-octylphenol, and dried at about 100°C. The dry material was then subjected briefly to a heat treatment at220° C. The material treated in this way had a significantly whiterappearance than the untreated material.

The use of a compound of the formula (A) or (C) instead of the compoundof the formula (B) produced similar results.

TABLE 1 Spectral data of selected optical brighteners AbsorptionExtinction Emission Compound λ_(max) [nm] lg ε λ_(max) [nm] 1 334 4.85359, 378 2 342 5.11 385, 406 3 344 5.23 395, 416 4 344 405, 422 5 353391, 412 6 363 392, 413 7 330 355, 373, 393

TABLE 2 Thermochemical data of selected spiro compounds Melting pointThermal degradation Compound [° C.] (5% weight loss) 1 296 425 2 408 5503 438 585 8 316 465 6 365 565 7 337 — Cpd. 1:2,2′,7,7′-tetraphenyl-9,9′-spirobifluorene (Ex. 3) Cpd. 2:2,2′,7,7′-tetrakis(biphenyl-4-yl)-9,9′-spirobifluorene (Ex. 4) Cpd. 3:2,2′,7,7′-tetrakis(terphenyl-4-yl)-9,9′-spirobifluorene Cpd. 4:2,2′,7,7′-tetrakis(quaterphenyl-4-yl)-9,9′-spirobifluorene Cpd. 5:2,2′,7,7′-tetrakis(4′-methoxybiphenyl-4-yl)-9,9′-spirobifluorene Cpd. 6:2,2′,4,4′,7,7′-hexakis(biphenyl-4-yl)-9,9′-spirobifluorene Cpd. 7:2,2′-bis[(5(p-t-butylphenyl-1,3,4-oxadiazol-2-yl]-9,9′-spirobifluoreneCpd. 8: 2,2′,4,4′,7,7′-hexaphenyl-9,9′-spirofluorene.

What is claimed is:
 1. A method of optically brightening which comprisesadding to a material to be optically brightened one or more spirocompounds of the formula

where K¹ and K², which are identical or different, are conjugatedsystems, and ψ is C, Si, Ge, Sn or Pb.
 2. The method as claimed in claim1, wherein ψ is C or Si.
 3. The method as claimed in claim 2, wherein ψis C.
 4. The method as claimed in claim 1, which comprises aspirofluorene of the formula (II),

where ψ is C, Si, Ge, Sn or Pb, and the benzo groups, are independentlyof one another, can be substituted with an unsubstituted aryl or arylsubstituted with an aromatic group(s) that can be substituted with alkylgroups and the aromatic groups optionally containing heteroatoms, and/orfused.
 5. The method as claimed in claim 1, wherein the Spiro compoundsare 2,2′,4,4′,7,7′-hexakis(biphenylyl)-9,9′-spirobifluorene;2,2′,4,4′,7,7′-hexakis(terphenylyl)-9,9′-spirobifluorene;2,2′,4,4′,7,7′-hexakis(quaterphenylyl)-9,9′-spirobifluorene; or2,2′,4,4′,7,7′-hexakis(pentaphenylyl)-9,9′-spirobifluorene.
 6. Themethod as claimed in claim 2, which comprises a spirobifluorenederivative of the formula (IIIIa) to (IIIg): IIIa) K═L═M═N and is agroup of the formula:

R′═C₁-C₂₂-Alkyl, C₂H₄SO₃— IIIb) K═M═H and N═L and is a group of theformula:

IIIc) K═M and is a group of the formula:

R′═C₁-C₂₂-Alkyl, C₂H₄SO₃— and N═L and is a group of the formula:

IIId) K═M and is a group of the formula:

and N═L and is a group of the formula:

R′═C₁-C₂₂-Alkyl, C₂H₄SO₃ ⁻ Ille) K═L═H and M═N and is a group of theformula:

IIIf) K═M and is a group of the formula:

R′═C₁-C₂-Alkyl, C₂H₄SO₃ ⁻ and M═N and is a group of the formula:

IIIg) K═L and is a group of the formula:

and M═N and is the group of the formula:

R′═C₁-C₂₂-Alkyl, C₂H₄SO₃ ⁻.
 7. The method thereof as claimed in claim 1,which comprises a spirobifluorene derivative of the formula (III),

where K, L, M, N are identical or different and are a group of thefollowing formulae:

R is identical or different and is as defined for K, L, M, N or is —H, alinear or branched alkyl, alkoxy or carboalkoxy group having form 1 to22 carbon atoms, —CN, —NO₂, —NR²R³, —N⁺R²R³R⁴, NOR²R³, —Ar or —O—Ar; Aris phenyl, biphenyl, 1-naphthyl, 2-naphthyl, 2-thienyl or 2-furanyl,where each of these groups optionally carry one or two radicals R, m, nand p are identical or different and are 0 1, 2, 3, 4 or 5; X and Y areidentical or different and are CR or N; Z is —O—, —S—, —NR—, CR′R—,—CH═CH═ or —CH═N—; R¹ is as defined for R; R², R³ and R⁴ are identicalor different and are H, a linear or branched alkyl group having from 1to 22 carbon atoms, —Ar or 3-methylphenyl.
 8. An optical brightenerwhich contains a material and a. which has a fluoroescence quantum yieldof ≧40% in solid form, and b. an emission maximum in the range from 380to 750 nm, measured at room temperature, decreases by no greater than25%, relative to an initial state, after the material, applied in athickness of no greater than 1 μm to a quartz substrate, has been heatedto 250° C. in an inert atmosphere at a pressure no greater than 1 mbarfor 30 min.
 9. The optical brightener as claimed in claim 7, which has afluorescence quantum yield in the solid of ≧50%.
 10. The opticalbrightener as claimed in claim 9, wherein the emission maximum is in therange from 380 to 750 nm, measured at room temperature decreases by nogreater than 20% relative to the initial state for thermal treatment.11. The optical brightener as claimed in claim 10, wherein the emissionmaximum is no greater than 15% relative to the initial state beforethermal treatment and the fluorescence quantum yield of ≧60%.
 12. Theoptical brightener as claimed in claim 8, wherein the material is aSpiro compound of formula (V)

where K, L, M, N are identical or different and are a group of thefollowing formulae:

R is identical or different and is as defined for K, L, M, N or is —H, alinear or branched alkyl, alkoxy or carboalkoxy group having form 1 to22 carbon atoms, —CN, —NO₂, —NR²R³, —N⁺R²R³R⁴, NOR²R³, —Ar or —O—Ar; Aris phenyl, biphenyl, 1-naphthyl, 2-naphthyl, 2-thienyl or2-furanyl,where each of these groups optionally carry one or two radicals R; m, nand p are identical or different and are 0, 1, 2, 3, 4 or 5; X and Y areidentical or different and are CR or N; Z is —O—, —S—, —NR—, CR¹R—,—CH═CH═ or —CH═N—: R¹ is as defined for R; R², R³ and R⁴ are identicalor different and are H, a linear or branched alkyl group having from 1to 22 carbon atoms, —Ar or 3-methylphenyl.
 13. The optical brightener asclaimed in claim 12 wherein R is identical or different and is hydrogen,a linear or branched alkyl, alkoxy, carboalkoxy group having from 1 to12 carbon atoms, —SO₂CH₃, —CF₃, halogen, —SO₃H, —SO₂Na(K), —PO(OC₂H₅)₂,—CH₃OSO₃—, —N(CH₃)₃ ⁺, or —O—(CH₂)₂)— N⁺(CH₃)(CH₂H₅)₂ and n is 0.